Effect of Damper Modelling and the Fault Clearing Process on Response Torque and Stressing of Turbine-Generator Shafts

The paper discusses the effect damper circuit modelling and the current interruption process following clearance of grid network disturbances has on machine transient response. Parameters for a 2-direct-axis and 3-quadrature-axis damper circuit model are given, as are those for lower-order damper model equivalents. Torques obtained following clearance of typical L-L-L and L-L non-ground system disturbances at fault current zeros or by simultaneous interruption for detailed and reduced damper models are illustrated. Further, the effect damper circuit modelling has on peak torque response following clearance of supply network disturbances at fault current zeros, sustained L-L-L and L-L stator terminals short-circuits and worst-case malsynchronisation is depicted.